polymers

Article

Extraction and Characterization of Natural Cellulosic Fiberfrom Pandanus amaryllifolius Leaves

Z. N. Diyana 1, R. Jumaidin 2,* , M. Z. Selamat 1, R. H. Alamjuri 3,* and Fahmi Asyadi Md Yusof 4

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Citation: Diyana, Z.N.; Jumaidin, R.;

Selamat, M.Z.; Alamjuri, R.H.; Md

Yusof, F.A. Extraction and

Characterization of Natural Cellulosic

Fiber from Pandanus amaryllifolius

Leaves. Polymers 2021, 13, 4171.

https://doi.org/10.3390/

polym13234171

Academic Editors: Domenico Acierno

and Swarup Roy

Received: 31 August 2021

Accepted: 11 November 2021

Published: 29 November 2021

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4.0/).

1 Fakulti Kejuruteraan Mekanikal, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, Durian Tunggal,Melaka 76100, Malacca, Malaysia; nurdiyanazakuan@gmail.com (Z.N.D.); zulkeflis@utem.edu.my (M.Z.S.)

2 Fakulti Teknologi Kejuruteraan Mekanikal dan Pembuatan, Universiti Teknikal Malaysia Melaka,Hang Tuah Jaya, Durian Tunggal, Melaka 76100, Malacca, Malaysia

3 Faculty of Tropical Forestry, Universiti Malaysia Sabah, Jalan UMS, Kota Kinabalu 88400, Sabah, Malaysia4 Malaysian Institute of Chemical & Bioengineering Technology (UniKL MICET), Universiti Kuala Lumpur,

Taboh Naning, Alor Gajah, Melaka 78000, Malacca, Malaysia; fahmiasyadi@unikl.edu.my* Correspondence: ridhwan@utem.edu.my (R.J.); rhanim@ums.edu.my (R.H.A.)

Abstract: Pandanus amaryllifolius is a member of Pandanaceae family and is abundant in south-east Asian countries including Malaysia, Thailand, Indonesia and India. In this study, Pandanusamaryllifolius fibres were extracted via a water retting extraction process and were investigated aspotential fibre reinforcement in polymer composite. Several tests were carried out to investigatethe characterization of Pandanus amaryllifolius fibre such as chemical composition analysis whichrevealed Pandanus amaryllifolius fibre’s cellulose, hemicellulose and lignin content of 48.79%, 19.95%and 18.64% respectively. Material functional groups were analysed by using Fourier transforminfrared (FTIR) spectroscopy and X-ray diffraction analysis confirming the presence of celluloseand amorphous substances in the fibre. The morphology of extracted Pandanus amaryllifolius fibrewas studied using a scanning electron microscope (SEM). Further mechanical behaviour of fibrewas investigated using a single fibre test with 5 kN cell load and tensile strength was found tobe 45.61 ± 16.09 MPa for an average fibre diameter of 368.57 ± 50.47 µm. Meanwhile, moisturecontent analysis indicated a 6.00% moisture absorption rate of Pandanus amaryllifolius fibre. Thethermogravimetric analysis justified the thermal stability of Pandanus amaryllifolius fibre up to 210 ◦C,which is within polymerization process temperature conditions. Overall, the finding shows thatPandanus amaryllifolius fibre may be used as alternative reinforcement particularly for a bio-basedpolymer matrix.

Keywords: Pandanus amaryllifolius fibre; natural fibres; composite

1. Introduction

Changes from the dominant usage of synthetic fibre to natural fibre indicate the riseof awareness among people around the world regarding the negative environmentalimpact that synthetic fibre brings which may damage human health. Synthetic polymersproduction utilized a large amount of energy which produces environmental pollutantsduring the production and recycling of synthetic composites [1]. The implementationof natural fibre-reinforced polymer (NFRP) composites has become an emerging trenddriven by stringent environmental legislation that focuses on the development of more eco-friendly materials as an alternative to substitute synthetic composites. The incorporationof natural fibres in composite has presented many improvements in terms of favourabletensile properties, reduced health hazards, acceptable insulating properties, low densityand decreased energy consumption [2]. Furthermore, cellulosic material has been widelyutilized in many applications such as cellulose nanofibers in food packaging, drug deliveryand biomedicine applications; chitosan widely used in biosensors and tissue engineering,membrane separation and treatment of water applications; and hybrid of bacterial cellulose

Polymers 2021, 13, 4171. https://doi.org/10.3390/polym13234171 https://www.mdpi.com/journal/polymers

Polymers 2021, 13, 4171 2 of 16

and chitin nanofibers have produced nanocomposite film that provides an excellent barrierto act as the antioxidant and antibacterial film [3]. Besides that, many studies have beenconducted with regards to the incorporation of natural fibre in composite applicationswhich have proven that natural fibre has remarkable advantages and is a promising methodto replace synthetic polymer [4–9].

Natural fibres can be simply defined as fibres that are not synthetic or man-made.They can be sourced from plants, animals or minerals where would be the common clas-sification of natural fibres. In general, most common natural fibres come from plantsand are composed of cellulose, thus making the fibre hydrophilic due to the presence ofpoly(1,4-β-D-anhydroglucopyranose) units which contain hydroxyl groups that enablethem to form strong hydrogen bonds [10,11]. They are also called lignocellulosic fibres sincetheir cellulose fibrils are embedded in the lignin matrix [12]. However, natural fibres prop-erties and structural parameters differ among plants depending on the species, growingenvironment, topographical location and preparation sample fibre method. The plant cellwall is composed of cellulose, hemicellulose and lignin where cellulose is the fundamentalcomposition of the fibre. [12]. Cellulose is an organic polysaccharide that is composed ofthousands of D-glucose units resulting from condensation via β(1→4)-glycosidic bondswhich permit cellulose to have physical and chemical properties that demonstrate hightensile strength, are environmentally friendly, non-toxic and totally renewable [13]. Hemi-cellulose is known as a branching polysaccharide polymer made up of glucose and othertypes of sugar groups including xylose, galactose, arabinos and mannose [11]. Lignin iscomposed largely of phenylpropane and is the second most abundant component aftercellulose, responsible for cementing cellulose microfibrils as well as protecting celluloseand hemicellulose contributes rigidity and also carries out water transport [4]. Both ligninand hemicellulose are amorphous polymers and cellulose is a semicrystalline polymer.

Pandanus amaryllifolius is a tropical plant and a member of the Pandanaceae family. Itis reported that there are more than 600 known species from the Pandanaceae family [13].Pandanus amaryllifolius is one of the species that is known as an endemic plant to Malaysiaand is famously called as pandan wangi. It is famous with regards to its unique fragrantleaves which are widely used for flavouring in the cuisines of the Southeast Asia region.Nevertheless, its species member called Pandanus tectorius has flowers that are scentedbut not the leaves [14]. The distinct flavour aroma from pandan wangi species is due tothe presence of a high amount of 2-acetyl-1-pyrroline (2AP) [15]. Despite its unique aromaand colouring, pandan wangi also has been used traditionally as medicine for decades andis proven to enhance the immune system and anti-tumour agents [16]. Besides that, it isalso reported that Pandanus amaryllifolius extract is able to reduce blood glucose levels aswell as shows improvement in insulin resistance [17]. Table 1 shows Pandanus species andapplications based on reported journals.

Table 1. Pandan species and potential applications.

Type of Pandan Potential Application References

Pandanus ceylanicus Polymer composite [13]Pandanus tectorius Natural fiber [18]

Pandanus utilis Low cost paper [19]Pandanus amaryllifolius Polymer composite [20,21]

Pandanus tectorius Pharmaceutical, medicine [16]Pandanus amaryllifolius Pharmaceutical, medicine [17]Pandanus odoratissimus Traditional medicine [22]Pandanus amaryllifolius Packaging application [23]

Since Pandanus amaryllifolius plant has various applications and benefits, final productsfrom extraction process or filtrate are taken out for further processes to leave Pandanusamaryllifolius fibre residue as a by-product. The remaining Pandanus amaryllifolius residuesare usually unused and then discarded as waste. It is reported that about 1 kilogram ofdried powder of pandan wangi can yield pandan extract of about 250 g [16]. Thus, if a huge

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scale of Pandanus amaryllifolius extract is produced this will contribute to the larger amountof pandan wangi waste that would be discarded. Moreover, since Pandanus amaryllifoliusfibre is a source of lignocellulose which is abundant, can be obtained at low cost and isrenewable, this would turn it into a suitable candidate for reinforcement agent in compositematerial application. Hence, it would be waste if the by-product is not fully utilized yet ithas good potential to be recycled and able to produce to be another product.

A study reported by Adhamatika et al. [24], characterized physiochemical Pandanusamaryllifolius leaves in an attempt to convert the leaves to powder form for a variety ofapplications. Different parts of pandan leaves were taken; young and old leaves, and under-gone three different drying methods; cabinet, vacuum and freeze-drying, prior turned intopandan powder. Although the investigation of physiochemical was conducted, the studyhas only focused on the non-cellulosic content in the pandan powder including ash content(%), chlorophyll content (mg/g), phenolic content (mg/g) and antioxidant (ppm) and nocellulosic information such as cellulose and hemicellulose content were demonstratedand no mechanical test conducted as the leaves were all converted into powder. Thus,the Pandanus amaryllifolius leaves characterization has not been well studied as sourceof fibre composite. Another study reported by Ooi et al. [25], focused on the potentialdevelopment of new antiviral protein from purification and characterization of Pandanusamaryllifolius leaves. It was observed that the composition of lectin, designated Pandanin,possessed antiviral activities against human viruses namely herpes simplex virus type-1(HSV-1). The extraction of lectin in the Pandanus amaryllifolius leaves was undertakenthrough a saline extract that underwent a few processes such as monium sulfate precip-itation, affinity chromatography and gel filtration. It is interesting to acknowledge onthe potential of Pandanin in Pandanus amaryllifolius could be a good candidate for a newclass of anti-HIV or other antiviral agents. Therefore, it is clear that the reports of bothAdhamatika et al. [24] and Ooi et al. [25] do not focus on the fibre characterization asthe potential of fibre reinforcement.

Although, there are several studies reported on the potential of Pandanus amaryllifoliusfibre as composite fillers application such as Pandanus amaryllifolius fibre in low-densitypolyethylene (LDPE) composite [23] and in epoxy resin composite [26]. However, tothe best of our knowledge, there has been no research carried out on the characterizationof Pandanus amaryllifolius fibre that comprehensively focused on its physicochemical andmechanical properties as a potential reinforcement agent. Hence, the study reported inthis article focuses on the extraction and characterization of the physical, chemical andmechanical properties of Pandanus amaryllifolius fibre for possible utilization as fillers inpolymer reinforcement matrix.

2. Materials and Methods2.1. Materials

The Pandanus amaryllifolius (pandan wangi) leaves collected from rural area of Bahau(Negeri Sembilan, Malaysia) were used in this study. Pandanus amaryllifolius fibre (PAF)were extracted from fresh leaves. Samples were characterized in short length fibre form asshown in Figure 1h except for mechanical testing.

2.2. Pandanus amaryllifolius Fibre Extraction

The extraction of PAF involved in this study used the most common fibre extractiontechnique known as water retting. This technique was carried out by introducing moistureand chemical enzymatic reaction to extract the fibre in the pandan wangi leaves. Initially,bundles of pandan wangi leaves were cleaned and chopped into 12 cm × 3 cm pieces.Then the leaves were then placed in stagnant water to undergo water retting process for8 weeks. Throughout the process, it was observed that the freshly collected pandan wangileaves were green in colour at the beginning and changed to yellow-brownish colour after8 weeks of water retting. The retted leaves were washed in running water and the pandanwangi fibres were removed by manual peeling. The extracted fibres were then cleaned

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and allowed to dry under direct sunlight for 1 day. After that, the extracted pandan wangifibres were further dried in the oven because drying under the sunlight is not enough toremove all the moisture in extracted fibres. The fibres were then placed in the oven for6 h at 80 ◦C. Some of the fibres were taken and ground using a disc mill to make the shortfibre form. Both ground (short fibres) and unground fibres were kept in the zip-locked baguntil further use. The images of different steps during the retting process are provided inFigure 1 below.

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ture and chemical enzymatic reaction to extract the fibre in the pandan wangi leaves. In-itially, bundles of pandan wangi leaves were cleaned and chopped into 12 cm × 3 cm pieces. Then the leaves were then placed in stagnant water to undergo water retting process for 8 weeks. Throughout the process, it was observed that the freshly collected pandan wangi leaves were green in colour at the beginning and changed to yel-low-brownish colour after 8 weeks of water retting. The retted leaves were washed in running water and the pandan wangi fibres were removed by manual peeling. The ex-tracted fibres were then cleaned and allowed to dry under direct sunlight for 1 day. After that, the extracted pandan wangi fibres were further dried in the oven because drying under the sunlight is not enough to remove all the moisture in extracted fibres. The fibres were then placed in the oven for 6 h at 80 °C. Some of the fibres were taken and ground using a disc mill to make the short fibre form. Both ground (short fibres) and unground fibres were kept in the zip-locked bag until further use. The images of different steps during the retting process are provided in Figure 1 below.

(a)

(b)

(c)

(d)

(e)

(f)

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(g)

(h)

Figure 1. Pictorial view of fibre extraction (a) Pandanus amaryllifolius plant; (b) cut bulk of leaves; (c) leaves cleaned and immersed in the water; (d) after 2 weeks; (e) skin degraded and removal of fi-bres; (f) extracted fibres collected and dried under sunlight; (g) ungrounded fibres after being fur-ther dried in oven; (h) ground (short fibres) PAF.

2.3. Characterization 2.3.1. Determination of Chemical Composition

The Pandanus amaryllifolius fibres (PAF) chemical composition was evaluated via neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL), as well as ash content analysis. Using Equations (1) and (2), the cellulose and hemicellulose percentages can be determined respectively:

Cellulose = ADF − ADL (1)

Hemicellulose = NDF − ADF (2)

2.3.2. Fibre Length and Diameter PAF fibre length was measured from the extracted fibre obtained after water retting

and drying. Meanwhile, fibre diameter was evaluated under an optical microscope, Zeiss (Axiovert 200; Carl Zeiss Light Microscopy, Göttigen, Germany) that measured 15 indi-vidual fibre samples. The average diameter was randomly measured at three different positions of each image and the average value was determined.

2.3.3. Moisture Content Five samples were prepared for the moisture content investigation. The weight of

the samples before (Wi) was recorded prior to being heated in an oven for 24 h at 105 °C. The final weight after heating (Wf) was recorded after constant weight was obtained to ensure no moisture remained in the sample. The moisture content of the samples was determined using the following Equation (3):

Moisture content (%) = × 100 (3)

2.3.4. Scanning Electron Microscope (SEM) Sample’s morphology was observed by using a scanning electron microscope (SEM)

machine, model Zeiss Evo 18 Research, (Jena, Germany) with an acceleration voltage of 10 kV.

2.3.5. Mechanical Testing The ASTM D3379 (1998) guideline was adopted in the evaluation of the tensile

properties of PAF by using an Instron universal testing machine (5556, Norwood, MA, USA) with 5 kN load cell capacity. Experimentation was performed with 30 mm gauge length and 1 mm/min crosshead speed. To ensure an adequate fibre fastening to the ten-

Figure 1. Pictorial view of fibre extraction (a) Pandanus amaryllifolius plant; (b) cut bulk of leaves;(c) leaves cleaned and immersed in the water; (d) after 2 weeks; (e) skin degraded and removalof fibres; (f) extracted fibres collected and dried under sunlight; (g) ungrounded fibres after beingfurther dried in oven; (h) ground (short fibres) PAF.

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2.3. Characterization2.3.1. Determination of Chemical Composition

The Pandanus amaryllifolius fibres (PAF) chemical composition was evaluated vianeutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL),as well as ash content analysis. Using Equations (1) and (2), the cellulose and hemicellulosepercentages can be determined respectively:

Cellulose = ADF − ADL (1)

Hemicellulose = NDF − ADF (2)

2.3.2. Fibre Length and Diameter

PAF fibre length was measured from the extracted fibre obtained after water rettingand drying. Meanwhile, fibre diameter was evaluated under an optical microscope, Zeiss(Axiovert 200; Carl Zeiss Light Microscopy, Göttigen, Germany) that measured 15 indi-vidual fibre samples. The average diameter was randomly measured at three differentpositions of each image and the average value was determined.

2.3.3. Moisture Content

Five samples were prepared for the moisture content investigation. The weight ofthe samples before (Wi) was recorded prior to being heated in an oven for 24 h at 105 ◦C.The final weight after heating (Wf) was recorded after constant weight was obtained toensure no moisture remained in the sample. The moisture content of the samples wasdetermined using the following Equation (3):

Moisture content (%) =Wi −W f

Wi× 100 (3)

2.3.4. Scanning Electron Microscope (SEM)

Sample’s morphology was observed by using a scanning electron microscope (SEM)machine, model Zeiss Evo 18 Research, (Jena, Germany) with an acceleration voltageof 10 kV.

2.3.5. Mechanical Testing

The ASTM D3379 (1998) guideline was adopted in the evaluation of the tensile proper-ties of PAF by using an Instron universal testing machine (5556, Norwood, MA, USA) with5 kN load cell capacity. Experimentation was performed with 30 mm gauge length and1 mm/min crosshead speed. To ensure an adequate fibre fastening to the tensile machine,fibre was glued earlier to a rectangular structure of 20 mm in width and 50 cm in length asshown in Figure 2a and testing assembly is shown as Figure 2b.

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sile machine, fibre was glued earlier to a rectangular structure of 20 mm in width and 50 cm in length as shown in Figure 2a and testing assembly is shown as Figure 2b.

(a)

(b)

Figure 2. Tensile testing; (a) fastening to structure; (b) testing assembly.

2.3.6. Fourier-Transform Infrared (FTIR) Spectrometry Fourier transform infrared (FT-IR) spectroscopy was used to investigate the inter-

molecular interaction and presence of functional group of PAF. Spectra of the material were obtained using JASCO FTIR-6100 Spectrometer (Japan). FT-IR spectra of the sample was collected in the range of 4000 to 500 cm−1 at resolution of 2 cm−1.

2.3.7. Thermogravimetric Analysis (TGA) Thermogravimetric analysis (TGA) was carried out using a Mettler-Toledo AG an-

alyzer (Greifensee, Switzerland). The test was performed in a temperature range between 30 and 600 °C in inert (nitrogen) atmosphere heating rate of 20 °C/min with a flowrate 20 mL/min. A sample of 5–10 mg of the composite was heated in an alumina crucible pan. Before the thermal study, the samples were pre-conditioned for at least 48 h at 53%.

2.3.8. X-ray Diffraction (XRD) Analysis The X-ray diffraction was conducted using a Rigaku D/max 2500 X-ray powder dif-

fractometer (Rigaku, Tokyo, Japan) with Cu radiation run at 40 kV and 30 mA with 0.15406 nm light wavelength. The scanning rate of 2° min−1 in the range of diffraction angle 10° to 40° at room temperature was used to scan the samples. The crystallinity in-dex (CI) was computed using the subsequent Segal expression, Equation (4): 𝐶𝐼 = 𝐼 − 𝐼𝐼 × 100% (4)

where I002 and Iam represent peak intensities of the crystalline and amorphous fractions, respectively. The crystallite size (CS) was determined using Scherrer’s formula as shown in Equation (5), 𝐶𝑆 = 𝑘𝜆 βcosƟ × 100% (5)

where k = 0.89 (Scherrer’s constant), λ = 0.1541 nm is the radiation wavelength, β is the peak’s full-width at half-maximum in radians, and θ is the corresponding Bragg angle.

3. Results and Discussion 3.1. Determination of Chemical Properties

Table 2 presents the chemical composition of Pandanus amaryllifolius fibre in com-parison with other natural fibres. Mechanical properties and biodegradability of fibre depend on its chemical composition [27]. From Table 2, Pandanus amaryllifolius fibre shows value of cellulose content of 48.79% comparable to sugarcane fibre and Arenga pinnata fibre, 48% and 43.88% respectively, and shows lower cellulose content than other

Figure 2. Tensile testing; (a) fastening to structure; (b) testing assembly.

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2.3.6. Fourier-Transform Infrared (FTIR) Spectrometry

Fourier transform infrared (FT-IR) spectroscopy was used to investigate the inter-molecular interaction and presence of functional group of PAF. Spectra of the material wereobtained using JASCO FTIR-6100 Spectrometer (Japan). FT-IR spectra of the sample wascollected in the range of 4000 to 500 cm−1 at resolution of 2 cm−1.

2.3.7. Thermogravimetric Analysis (TGA)

Thermogravimetric analysis (TGA) was carried out using a Mettler-Toledo AG ana-lyzer (Greifensee, Switzerland). The test was performed in a temperature range between30 and 600 ◦C in inert (nitrogen) atmosphere heating rate of 20 ◦C/min with a flowrate20 mL/min. A sample of 5–10 mg of the composite was heated in an alumina crucible pan.Before the thermal study, the samples were pre-conditioned for at least 48 h at 53%.

2.3.8. X-ray Diffraction (XRD) Analysis

The X-ray diffraction was conducted using a Rigaku D/max 2500 X-ray powderdiffractometer (Rigaku, Tokyo, Japan) with Cu radiation run at 40 kV and 30 mA with0.15406 nm light wavelength. The scanning rate of 2◦ min−1 in the range of diffractionangle 10◦ to 40◦ at room temperature was used to scan the samples. The crystallinity index(CI) was computed using the subsequent Segal expression, Equation (4):

CI =I002 − Iam

I002× 100% (4)

where I002 and Iam represent peak intensities of the crystalline and amorphous fractions,respectively. The crystallite size (CS) was determined using Scherrer’s formula as shownin Equation (5),

CS =kλ

β cosθ× 100% (5)

where k = 0.89 (Scherrer’s constant), λ = 0.1541 nm is the radiation wavelength, β isthe peak’s full-width at half-maximum in radians, and θ is the corresponding Bragg angle.

3. Results and Discussion3.1. Determination of Chemical Properties

Table 2 presents the chemical composition of Pandanus amaryllifolius fibre in compari-son with other natural fibres. Mechanical properties and biodegradability of fibre dependon its chemical composition [27]. From Table 2, Pandanus amaryllifolius fibre shows value ofcellulose content of 48.79% comparable to sugarcane fibre and Arenga pinnata fibre, 48%and 43.88% respectively, and shows lower cellulose content than other natural fibres suchas Calotropis gigantea, Ficus religiosa, Coccinia grandis, bamboo, jute, sisal, kenaf and acaciatortilis with cellulose content of 64.47%, 55.58%, 63.22%, 73.83%, 66%, 65%, 72% and 61.89%respectively. Meanwhile, cassava bagasse, Pandanus tectorius and Tridax procumbens showlower cellulose value of 27%, 37.3% and 32% respectively. High cellulose content in fibrecontributes to the enhancement of mechanical properties [11]. However, from the datatabulated in Table 2, Pandanus amaryllifolius fibre exhibits considerably low cellulose contentthat might be reflected in the low tensile value obtained in mechanical testing, besidesthe influence of fibre diameter. This also might be attributed to the presence of a highcontent of amorphous substances in Pandanus amaryllifolius fibre such as hemicellulose,lignin, ash and waxes [28].

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Table 2. Comparative chemical composition of Pandanus amaryllifolius fibre and other natural fibres.

Fibre Cellulose(%)

Hemicellulose(%)

Lignin(%)

Ash(%) Ref.

Pandanus amaryllifolius 48.79 19.95 18.64 1.08 -Cymbopogan citratus 37.56 29.29 11.14 4.28 [29]Calotropis gigantea 64.47 9.64 13.56 3.13 [30]Tridax procumbens 32.00 6.80 3.00 0.71 [31]

Ficus religiosa 55.58 13.86 10.13 4.86 [32]Coccinia grandis 63.22 - 24.42 - [33]

Bamboo 73.83 12.49 10.5 - [34]Sugarcane 48.00 14.60 12.10 12.10 [35]

Jute 66.00 17.00 12.50 - [36]Sisal 65.00 12.00 9.90 - [36]

Kenaf 72.00 20.30 9.00 - [36]Cassava bagasse 27.00 30.00 2.70 - [37]

Acacia tortilis 61.89 - 21.26 4.33 [27]Arenga pinnata (sugar palm) 43.88 7.24 33.24 1.01 [38]

Pandanus tectorius 37.30 34.40 22.60 24.00 [11]

The biological role of hemicellulose is to strengthen plant cell walls by interactionwith cellulose. Pandanus amaryllifolius fibre hemicellulose content of 19.95% is comparableto kenaf fibre, 20.3%, and jute fibre, 17%. It has relatively high hemicellulose content ascompared to all other natural fibres except for kenaf, cassava bagasse and Pandanus tectoriuswith hemicellulose content of 20.3%, 30% and 34.4%, respectively. Besides that, the presenceof hydrophobic substances such as lignin makes it less susceptible to moisture as well asproviding better fibre stability and rigidity; however, it lowers the fibre tensile strength.The lignin content in Pandanus amaryllifolius fibre was 18.64% making it comparable toAcacia tortilis, 21.26% and Pandanus tectorius, 22.6%. It is also seen to have higher lignincontent than bamboo, sugarcane, jute, sisal, kenaf and cassava bagasse at 10.5%, 12.1%,12.5%, 9.9%, 9% and 2.7% respectively. Ash content in Pandanus amaryllifolius fibre isrecorded at 1.08%, considered as among of the lowest in comparison to other natural fibrestabulated in Table 2 which determines it has less susceptibility to moisture when appliedin a humid environment. The value is in good agreement with the result obtained frommoisture content testing.

All chemical compositions exhibited in every plant natural fibre have their mainfunctionality and role in maintaining the rigidity of the plant structure and they comple-ment every constituent. However, it is worth noting that in filler composite application,the amount of cellulose in fibre becomes the main criteria that might influence the mechan-ical properties of the resulting composite.

3.2. Determination of Physical Properties

A total of 15 samples of Pandanus amaryllifolius fibre was picked randomly to deter-mine the average fibre length. The extracted fibre were chosen in dried condition afterundergoing the drying process as presented in Figure 1g. The average ultimate fibre lengthwas found in this study to be 45.07 ± 4.81 mm long (coefficient of variation, CV = 0.11).The coefficient of variation value shows the variability in the individual reading is smallmeaning the sample is fairly homogenous. In general, fibre physical properties are varieddepending on the climate, environmental condition, age and origin of fibre [11]. Besides,the Pandanus amaryllifolius fibres were collected from rural areas living alongside otherwild plants as displayed in Figure 1a. Physically, it can be observed that the collected fibreis bigger and longer in size compared to Pandanus amaryllifolius fibres that are cultivated inresidential areas.

Table 3 presents the diameter and moisture content of Pandanus amaryllifolius fibrecompared to other natural fibres. Fibre diameter plays a vital role in determining fracturesurface area thus reflecting the tensile value of the material in determining mechanical

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properties of the fiber. Thus, the diameter measurement of Pandanus amaryllifolius fibre isconducted under an optical microscope as displayed in Figure 3. Fibre average diameterwas found to be 368.57 ± 50.47 µm which is comparable to the diameter of Cissusquadran-gularis root (350 µm) and Coccinia grandis (543 ± 75 µm).

Table 3. Comparative physical properties of Pandanus amaryllifolius fibre and other natural fibres.

Fibre Diameter (µm) Moisture (%) Ref.

Pandanus amaryllifolius 368.57 ± 50.47 6.00 ± 0.13 -Cymbopogan citratus 326.67 ± 45.77 5.20 ± 2.28 [29]Calotropis gigantea 32.70 7.27 [30]Tridax procumbens 233.1 ± 9.9 11.20 [31]Juncus effuses L. 280 ± 56 - [39]Ficus Religiosa 25.62 9.33 [32]

Date palm rachis 88 ± 12 - [40]Coccinia grandis 543 ± 75 9.14 [33]

Cissusquadrangularis root 350 7.30 [41]Bamboo - 7.00 [34]

Acacia tortilis 480 6.47 [27]Arenga pinnata (sugar palm) 212.01 ± 2.17 8.36 [38]

(Note: Coefficient of variations of fibre diameter for Pandanus amaryllifolius fibre, CVFD = 0.14).

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3.2. Determination of Physical Properties A total of 15 samples of Pandanus amaryllifolius fibre was picked randomly to de-

termine the average fibre length. The extracted fibre were chosen in dried condition after undergoing the drying process as presented in Figure 1g. The average ultimate fibre length was found in this study to be 45.07 ± 4.81 mm long (coefficient of variation, CV = 0.11). The coefficient of variation value shows the variability in the individual reading is small meaning the sample is fairly homogenous. In general, fibre physical properties are varied depending on the climate, environmental condition, age and origin of fibre [11]. Besides, the Pandanus amaryllifolius fibres were collected from rural areas living alongside other wild plants as displayed in Figure 1a. Physically, it can be observed that the col-lected fibre is bigger and longer in size compared to Pandanus amaryllifolius fibres that are cultivated in residential areas.

Table 3 presents the diameter and moisture content of Pandanus amaryllifolius fibre compared to other natural fibres. Fibre diameter plays a vital role in determining fracture surface area thus reflecting the tensile value of the material in determining mechanical properties of the fiber. Thus, the diameter measurement of Pandanus amaryllifolius fibre is conducted under an optical microscope as displayed in Figure 3. Fibre average diameter was found to be 368.57 ± 50.47 μm which is comparable to the diameter of Cissusquad-rangularis root (350 μm) and Coccinia grandis (543 ± 75 μm).

Figure 3. Optical microscopy image of the Pandanus amaryllifolius fibre.

Furthermore, moisture content of Pandanus amaryllifolius fibre was the lowest among natural fibres as shown in Table 3. However, the moisture content of Pandanus amarylli-folius fibre is seen to be the lowest among others and comparable to Acacia tortilis and bamboo at 6.47% and 7.00%, respectively. Meanwhile, the moisture content of Tridax procumbens fibre showed the highest which at 11.20%. Moisture content plays an im-portant role in selecting the best properties of polymer products such as plastic packag-ing applications. Thus, the lower moisture content is preferable as it reflects the hydro-phobicity of the fibre material.

Table 3. Comparative physical properties of Pandanus amaryllifolius fibre and other natural fibres.

Fibre Diameter (μm) Moisture (%) Ref. Pandanus amaryllifolius 368.57 ± 50.47 6.00 ± 0.13 -

Cymbopogan citratus 326.67 ± 45.77 5.20 ± 2.28 [29] Calotropis gigantea 32.70 7.27 [30] Tridax procumbens 233.1 ± 9.9 11.20 [31]

Juncus effuses L. 280 ± 56 - [39] Ficus Religiosa 25.62 9.33 [32]

Figure 3. Optical microscopy image of the Pandanus amaryllifolius fibre.

Furthermore, moisture content of Pandanus amaryllifolius fibre was the lowest amongnatural fibres as shown in Table 3. However, the moisture content of Pandanus amaryllifoliusfibre is seen to be the lowest among others and comparable to Acacia tortilis and bambooat 6.47% and 7.00%, respectively. Meanwhile, the moisture content of Tridax procumbensfibre showed the highest which at 11.20%. Moisture content plays an important rolein selecting the best properties of polymer products such as plastic packaging applica-tions. Thus, the lower moisture content is preferable as it reflects the hydrophobicity ofthe fibre material.

3.3. Mechanical Testing

A total of 15 samples of fibre were chosen randomly to be tested under tensile testat a gauge length of 30 mm before obtaining the mechanical properties of the Pandanusamaryllifolius fibre. Figure 4 illustrates a typical stress-strain curve behaves quasi-linearlypresented an initial elastic region with a strong slope, (ε ≤ 1.5%), continued with non-linear elastic region between 2% to 5% strain and reached final softening phase up to8.3% maximum strain value. Besides, the elastic modulus was calculated from the elasticregion values raging between 0.5% and 1.5% as shown in Figure 4. In general, the fibredemonstrated brittle properties due to the sudden drop in stress value in the stress-straincurve which is in good agreement with other reported studies on natural fibres such asTridax procumbens [31], Juncus effsus L. [39] and Agave americana L. [42]. Typical yield point

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and breaking stress of Pandanus amaryllifolius fibre is labelled in Figure 4 and the elasticregion is found to be smaller than the plastic region which is similar to the stress-straincurve obtained for Juncus effsus L. [39], Agave americana L. [42] and Vernonia eleagnifolia [43].Unlike synthetic fibre, where the size and properties of the produced fibre can be controlledduring the manufacturing process before being applied, natural fibre exhibits variation indiameter for every single fibre strand obtained. Therefore, the average value of mechanicaltensile properties is displayed in Table 4 with standard deviation to show the variability inindividual reading being small, and the material is fairly homogenous compared to tensileresults extracted from different research studies.

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Date palm rachis 88 ± 12 - [40] Coccinia grandis 543 ± 75 9.14 [33]

Cissusquadrangularis root 350 7.30 [41] Bamboo - 7.00 [34]

Acacia tortilis 480 6.47 [27] Arenga pinnata (sugar palm) 212.01 ± 2.17 8.36 [38]

(Note: Coefficient of variations of fibre diameter for Pandanus amaryllifolius fibre, CVFD = 0.14).

3.3. Mechanical Testing A total of 15 samples of fibre were chosen randomly to be tested under tensile test at

a gauge length of 30 mm before obtaining the mechanical properties of the Pandanus am-aryllifolius fibre. Figure 4 illustrates a typical stress-strain curve behaves quasi-linearly presented an initial elastic region with a strong slope, (ε ≤ 1.5%), continued with non-linear elastic region between 2% to 5% strain and reached final softening phase up to 8.3% maximum strain value. Besides, the elastic modulus was calculated from the elastic region values raging between 0.5% and 1.5% as shown in Figure 4. In general, the fibre demonstrated brittle properties due to the sudden drop in stress value in the stress–strain curve which is in good agreement with other reported studies on natural fibres such as Tridax procumbens [31], Juncus effsus L. [39] and Agave americana L. [42]. Typical yield point and breaking stress of Pandanus amaryllifolius fibre is labelled in Figure 4 and the elastic region is found to be smaller than the plastic region which is similar to the stress–strain curve obtained for Juncus effsus L. [39], Agave americana L. [42] and Vernonia eleagnifolia [43]. Unlike synthetic fibre, where the size and properties of the produced fibre can be controlled during the manufacturing process before being applied, natural fibre exhibits variation in diameter for every single fibre strand obtained. Therefore, the average value of mechanical tensile properties is displayed in Table 4 with standard deviation to show the variability in individual reading being small, and the material is fairly homogenous compared to tensile results extracted from different research studies.

Figure 4. Typical stress–strain curve for Pandanus amaryllifolius fibre with magnification of elastic region. Figure 4. Typical stress-strain curve for Pandanus amaryllifolius fibre with magnification of elastic region.

Table 4. Comparison tensile properties of Pandanus amaryllifolius fibre with other natural fibre.

Fibre Tensile Strength,σ (MPa)

Tensile Modulus,E (GPa)

Elongation atBreak,ε (%)

Ref.

Pandanusamaryllifolius 45.61 ± 16.09 0.41 ± 0.18 8.17 ± 3.84 -

Cymbopogan citratus 43.81 ± 15.27 1.04 ± 0.33 0.84 ± 0.28 [29]Tridax procumbens 25.75 0.94 ± 0.09 2.77 ± 0.27 [31]

Acacia tortilis 71.63 4.21 1.33 [27]Juncus effuses L. 113 ± 36 4.38 ± 1.37 2.75 ± 0.6 [39]

Vernonia eleagnifolia 259.6 37.8 6.9 [43]Ficus Religiosa 433.32 ± 44 5.42 ± 2.6 8.74 ± 1.8 [32]

Coccinia grandis 424.24 26.52 16.00 [33]Date palm 530.5 21.9 3.6 [40]Bamboo 583.0 25.5 2.1 [44]

Kenaf 393–773 26.5 1.6 [36]Sisal 511–635 2.2–9.4 1.5 [36]

Kenaf 930.0 53.0 1.5 [36]

Sanyang et al. [12] found that the high cellulose content of fibre has a strong influenceon their mechanical properties and different parts of the plant contribute to the differentamounts of cellulose content from the fibre extracted. The study mentioned that sugarpalm fibre extracted from the frond part contained the highest cellulose content (66.49%) ascompared to bunch (61.76%) and trunk (40.56%) which leads to the highest fibre strengthbeing found at the frond part (421.4 MPa) rather than the bunch (365.1 MPa) and trunk(198.3 MPa). Therefore, this could relate from data tabulated in Tables 2 and 4, since

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Pandanus amaryllifolius is a leaf plant and tensile strength obtained is considerably lowerthan others which might be due to the cellulose content of fibre itself. A similar findinghas also been reported on the enhancement of mechanical properties as the cellulosecontent increased after chemical treatment on fibre was conducted [27]. In general, fromTable 4, the average tensile strength, elastic modulus, and elongation value of Pandanusamaryllifolius was found to be 45.61 ± 16.09 MPa, 0.41 ± 0.18 GPa, and 8.17 ± 3.84%,respectively. The tensile value found in the present work is higher than Cymbopogan citratus,43.81 ± 15.27 MPa [29] and Tridax procumbens, 25.75 MPa [31] which might be attributedto higher cellulose content found in Pandanus amaryllifolius fibre (48.79%) as compared toCymbopogan citratus (37.56%) and Tridax procumbens (32.00%). Meanwhile, Dawit et al. [27]reported better tensile strength of Acacia tortilis, 71.60 MPa than Pandanus amaryllifoliuswhich also could relate to higher cellulose content found at 61.89%.

In the meantime, elastic modulus calculated from this study demonstrated an almostsimilar value to 0.94 ± 0.09 GPa obtained from fibre named Tridax procumbens as reportedby Vijay et al. [31] and slightly lower than 1.04 ± 0.33 GPa reported for Cymbopogancitratus [29]. Moreover, Pandanus amaryllifolius fibre elongation at break is found to bean almost similar value of 8.74 ± 1.8% to Ficus Religiosa fibre studied by Arul et al. [32]while remaining higher than other fibres such as Cymbopogan citratus (0.84 ± 0.28%), Tridaxprocumbens (2.77 ± 0.27%), Acacia tortilis (1.30%), Juncus effuses L. (2.75 ± 0.6%), Vernoniaeleagnifolia (6.9%) and date palm (3.6%). In general, although the overall mechanicalproperties of Pandanus amaryllifolius fibre as tabulated in Table 4 is averagely lower thanother lignocellulosic fibres, it still can be considered as alternative reinforcement especiallyfor a bio-based polymer matrix which is typically use for low strength application such asbiodegradable packaging material.

3.4. Scanning Electron Microscope (SEM)

The SEM of PAF at magnification of 100× and 300× are shown in Figure 5a,b, re-spectively. In general, the surface micrograph of PAF is not smooth and is uneven withthe deposition of other substances. From the presented longitudinal image at 100×magnif-icent, it is observed that the fibre structure exhibits vertical alignments in the same directionof the fibre axis. This is might be attributed to the structure of PAF that is composed of mi-crofibrils, compactly aligned and bonded together by lignin, pectin and other non-cellulosicmaterials [4]. When the image is zoomed in at 300× magnification, Figure 5b, the structureof microfibrils can be seen and further prove the presence of lignin that is responsible forcementing cellulose microfibrils and protecting the structure. Similar results were reportedby other authors [38,45]. Other than that, we also found shapes of regularly distributedsemi-rectangular trays exist together along with PAF surface lines. The phenomenon mightbe exhibited in the deposition of amorphous substances including hemicellulose and ligninand might also be impurities that present during the binding process [40]. Nevertheless,the serration and uneven fibre surface somehow can help improve mechanical performance.It helps in enhancing the fibre-matrix interface in polymeric composite material, lockingthe fibre mechanically in the polymeric resin [45].

3.5. Fourier-Transform Infrared (FTIR) Spectrometry

The FTIR curve of Pandanus amaryllifolius fibre is displayed in Figure 6. The broad-band and peak occurred at 3332 cm−1 reflecting water adsorption and the presence ofthe hydroxyl (O–H) group in the fibre which also indicates the existence of cellulose, ligninand water [45]. The presence of water in the fibre was revealed by moisture content tests.Meanwhile, the absorbance peak in the 2919 cm−1 and 1732 cm−1 represents the stretchingof alkanes (C–H) and carboxyl group (C=O) of both cellulose and hemicellulose [38].The presence of (C=C) stretch from aromatic lignin is observed at wave peaks of 1672 cm−1.Besides that, the peak range of 1149–1414 cm−1 in the Pandanus amaryllifolius fibre spec-trum is associated to the (C=O) stretching vibration of ester linkage of the carboxylicgroup of ferulic and p-coumaric acids of hemicellulose and lignin [46]. Constituents of

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polysaccharide in cellulose confirm the stretching vibration of (C–O) and (O–H) that oc-curred at the radiation of 1023 cm−1. FTIR analysis verified the existence of cellulose andhemicellulose in the fibre’s structural composition.

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3.4. Scanning Electron Microscope (SEM) The SEM of PAF at magnification of 100× and 300× are shown in Figure 5a,b, re-

spectively. In general, the surface micrograph of PAF is not smooth and is uneven with the deposition of other substances. From the presented longitudinal image at 100× mag-nificent, it is observed that the fibre structure exhibits vertical alignments in the same direction of the fibre axis. This is might be attributed to the structure of PAF that is composed of microfibrils, compactly aligned and bonded together by lignin, pectin and other non-cellulosic materials [4]. When the image is zoomed in at 300× magnification, Figure 5b, the structure of microfibrils can be seen and further prove the presence of lig-nin that is responsible for cementing cellulose microfibrils and protecting the structure. Similar results were reported by other authors [38,45]. Other than that, we also found shapes of regularly distributed semi-rectangular trays exist together along with PAF surface lines. The phenomenon might be exhibited in the deposition of amorphous sub-stances including hemicellulose and lignin and might also be impurities that present during the binding process [40]. Nevertheless, the serration and uneven fibre surface somehow can help improve mechanical performance. It helps in enhancing the fi-bre-matrix interface in polymeric composite material, locking the fibre mechanically in the polymeric resin [45].

(a)

(b)

Figure 5. Longitudinal view of Pandanus amaryllifolius (pandan wangi) fibre by scanning electron microscope (SEM); (a) 100× magnification; (b) 300× magnification.

3.5. Fourier-Transform Infrared (FTIR) Spectrometry The FTIR curve of Pandanus amaryllifolius fibre is displayed in Figure 6. The broad-

band and peak occurred at 3332 cm−1 reflecting water adsorption and the presence of the hydroxyl (O–H) group in the fibre which also indicates the existence of cellulose, lignin and water [45]. The presence of water in the fibre was revealed by moisture content tests. Meanwhile, the absorbance peak in the 2919 cm−1 and 1732 cm−1 represents the stretching of alkanes (C–H) and carboxyl group (C=O) of both cellulose and hemicellulose [38]. The presence of (C=C) stretch from aromatic lignin is observed at wave peaks of 1672 cm−1. Besides that, the peak range of 1149–1414 cm−1 in the Pandanus amaryllifolius fibre spec-trum is associated to the (C=O) stretching vibration of ester linkage of the carboxylic group of ferulic and p-coumaric acids of hemicellulose and lignin [46]. Constituents of polysaccharide in cellulose confirm the stretching vibration of (C–O) and (O–H) that oc-curred at the radiation of 1023 cm−1. FTIR analysis verified the existence of cellulose and hemicellulose in the fibre’s structural composition.

Figure 5. Longitudinal view of Pandanus amaryllifolius (pandan wangi) fibre by scanning electron microscope (SEM);(a) 100×magnification; (b) 300×magnification.

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Figure 6. Fourier transform infrared (FTIR) spectra of Pandanus amaryllifolius fibre.

3.6. X-ray Diffraction Measurement The diffraction pattern for Pandanus amaryllifolius fibre is shown in Figure 7 and the

presence of three peaks can be observed. The highest intensity peak is found at 2𝜃 = 23.16°, average density peak at 2𝜃 = 16.78° and the lowest intensity peak occurred at 2𝜃 = 34.69°, which are denoted as the (002), (110) and (040) crystallographic planes, respec-tively [40]. The highest peak intensity (002) corresponds to the presence of semi-crystalline structure cellulose type I, associated to the parallel chain orientation with intra-sheet hydrogen bonds [47]. Meanwhile, the diffracted peak at intensity (110) proves the amorphous fraction in Pandanus amaryllifolius fibre [41]. This result is in corroboration with chemical and FTIR analysis results that confirm the presence of cellulose and amorphous substances.

High crystallinity values stipulate excellent mechanical properties of the fibre which can be identified from the sharpness of the diffraction peak where the sharper diffraction peak indicates a high crystallinity degree of the structure that might be influenced by the cellulose rigidity [48]. Segal’s peak equation Equation (4) is employed to find the crystal-linity index (CI) from the peaks found. The CI for Pandanus amaryllifolius fibre are calcu-lated found to be 37.09% and 4.95 nm. This CI value is comparable to Calotropis gigantea (36.00%), higher than Tridax procumbens (34.46%) and Juncus effuses L. (33.40%), but lower than Ficus religiosa (42.92), Pandanus tectorius (55.10%), Cissusquadrangularis root (56.60%), pigeon pea plant (65.89%) and date palm rachis (69.77%).

Crystalline size (CS) for Pandanus amaryllifolius fibre is calculated using Segal’s Equation (5) and found to be 4.95 nm. This value is within crystallite range size reported for other natural fibres such as Ficus religiosa (5.18 nm), Tridax procumbens (25.04 nm) and Juncus effuses L. (3.60 nm). The crystalline property of Pandanus amaryllifolius fibre is compared with the tested natural fibres shown in Table 5.

Figure 6. Fourier transform infrared (FTIR) spectra of Pandanus amaryllifolius fibre.

3.6. X-ray Diffraction Measurement

The diffraction pattern for Pandanus amaryllifolius fibre is shown in Figure 7 andthe presence of three peaks can be observed. The highest intensity peak is found at2θ = 23.16◦, average density peak at 2θ = 16.78◦ and the lowest intensity peak occurred at2θ = 34.69◦, which are denoted as the (002), (110) and (040) crystallographic planes, respec-tively [40]. The highest peak intensity (002) corresponds to the presence of semi-crystallinestructure cellulose type I, associated to the parallel chain orientation with intra-sheet hy-drogen bonds [47]. Meanwhile, the diffracted peak at intensity (110) proves the amorphousfraction in Pandanus amaryllifolius fibre [41]. This result is in corroboration with chemicaland FTIR analysis results that confirm the presence of cellulose and amorphous substances.

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Figure 7. X-ray diffraction pattern of Pandanus amaryllifolius fibre.

Table 5. Comparison table of crystalline properties of Pandanus amaryllifolius fibre with other nat-ural fibres.

Fiber C.I (%) C.S (nm) References Pandanus amaryllifolius 37.09 4.95 -

Cymbopogan citratus 35.20 - [29] Calotropis gigantea 36.00 - [30] Tridax procumbens 34.46 25.04 [31]

Juncus effuses L. 33.40 3.60 [39] Ficus Religiosa 42.92 5.18 [32]

Pandanus tectorius 55.10 - [11] Cissusquadrangularis root 56.60 7.04 [41]

Pigeon pea plant 65.89 11.60 [49] Date palm rachis 69.77 5.63 [40]

3.7. Thermogravimetric Analysis Figure 8 shows thermogravimetric analysis for Pandanus amaryllifolius fibre, both

TGA and DTG curves were plotted as a function of temperature. This thermal analysis is used to measure weight degradation as the material is heated. In general, three degrada-tion phases can be observed in Figure 8 which comprises small initial weight loss at the temperature range of 30–120 °C, major weight loss as the temperature rises from 220–420 °C, and final stage degradation afterwards until the maximum temperature was reached. The first stage with 7.84% weight loss corresponds to the evaporation of adsorbed moisture which is attributed to the hydrophilic nature of lignocellulosic materials [11,40]. After that, thermal stability is noted up to about 210 °C which reflects no appearance of significant peaks in both TGA and DTG curves showing that the work is in good agree-ment [39]. Then, major weight loss is observed, 67.70%, associated to the decomposition of glycosidic linkage cellulose and hemicellulose substances at the temperature range of 220–420 °C [41]. It is confirmed by the observation of the DTG peak curve at 370 °C which indicates the possible thermal decomposition of cellulose I and completion of 𝛼-cellulose decomposition [33]. Lastly, the final stage of degradation is associated to the fragmenta-tion of waxen substances such as lignin and observed at temperatures 420–500 °C with small weight loss of 11.32%. Last but not least, char residue is spotted at 13.14% at the highest temperature of 600 °C. This char residue is mainly composed of carbon or car-

Figure 7. X-ray diffraction pattern of Pandanus amaryllifolius fibre.

High crystallinity values stipulate excellent mechanical properties of the fibre whichcan be identified from the sharpness of the diffraction peak where the sharper diffrac-tion peak indicates a high crystallinity degree of the structure that might be influencedby the cellulose rigidity [48]. Segal’s peak equation Equation (4) is employed to findthe crystallinity index (CI) from the peaks found. The CI for Pandanus amaryllifolius fibreare calculated found to be 37.09% and 4.95 nm. This CI value is comparable to Calotropisgigantea (36.00%), higher than Tridax procumbens (34.46%) and Juncus effuses L. (33.40%), butlower than Ficus religiosa (42.92), Pandanus tectorius (55.10%), Cissusquadrangularis root(56.60%), pigeon pea plant (65.89%) and date palm rachis (69.77%).

Crystalline size (CS) for Pandanus amaryllifolius fibre is calculated using Segal’s Equa-tion (5) and found to be 4.95 nm. This value is within crystallite range size reported forother natural fibres such as Ficus religiosa (5.18 nm), Tridax procumbens (25.04 nm) and Juncuseffuses L. (3.60 nm). The crystalline property of Pandanus amaryllifolius fibre is comparedwith the tested natural fibres shown in Table 5.

Table 5. Comparison table of crystalline properties of Pandanus amaryllifolius fibre with othernatural fibres.

Fiber C.I (%) C.S (nm) References

Pandanus amaryllifolius 37.09 4.95 -Cymbopogan citratus 35.20 - [29]Calotropis gigantea 36.00 - [30]Tridax procumbens 34.46 25.04 [31]Juncus effuses L. 33.40 3.60 [39]Ficus Religiosa 42.92 5.18 [32]

Pandanus tectorius 55.10 - [11]Cissusquadrangularis root 56.60 7.04 [41]

Pigeon pea plant 65.89 11.60 [49]Date palm rachis 69.77 5.63 [40]

3.7. Thermogravimetric Analysis

Figure 8 shows thermogravimetric analysis for Pandanus amaryllifolius fibre, both TGAand DTG curves were plotted as a function of temperature. This thermal analysis is used tomeasure weight degradation as the material is heated. In general, three degradation phasescan be observed in Figure 8 which comprises small initial weight loss at the temperaturerange of 30–120 ◦C, major weight loss as the temperature rises from 220–420 ◦C, and final

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stage degradation afterwards until the maximum temperature was reached. The first stagewith 7.84% weight loss corresponds to the evaporation of adsorbed moisture which isattributed to the hydrophilic nature of lignocellulosic materials [11,40]. After that, thermalstability is noted up to about 210 ◦C which reflects no appearance of significant peaks inboth TGA and DTG curves showing that the work is in good agreement [39]. Then, majorweight loss is observed, 67.70%, associated to the decomposition of glycosidic linkagecellulose and hemicellulose substances at the temperature range of 220–420 ◦C [41]. It isconfirmed by the observation of the DTG peak curve at 370 ◦C which indicates the possiblethermal decomposition of cellulose I and completion of α-cellulose decomposition [33].Lastly, the final stage of degradation is associated to the fragmentation of waxen substancessuch as lignin and observed at temperatures 420–500 ◦C with small weight loss of 11.32%.Last but not least, char residue is spotted at 13.14% at the highest temperature of 600 ◦C.This char residue is mainly composed of carbon or carbonaceous material that cannotbe further degraded into smaller volatile fragments and will remain in the combustionchamber until the process ends. It also might be attributed to the presence of inorganicmatter that yields chars and may form the basis of quantitative estimation. Boumediriet al. [40] and Maache et al. [39] reported on char residue left at the end of combustion ofan amount of 3.64% for Juncus effuses L. fibre and 18.29% for date palm fibre, respectively.

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bonaceous material that cannot be further degraded into smaller volatile fragments and will remain in the combustion chamber until the process ends. It also might be attributed to the presence of inorganic matter that yields chars and may form the basis of quantita-tive estimation. Boumediri et al. [40] and Maache et al. [39] reported on char residue left at the end of combustion of an amount of 3.64% for Juncus effuses L. fibre and 18.29% for date palm fibre, respectively.

Figure 8. Thermogravimetric analysis (TGA) and DTG curves for Pandanus amaryllifolius fibre.

4. Conclusions The Pandanus amaryllifolius fibres were successfully extracted from plants via a water

retting extraction process. The Pandanus amaryllifolius fibres were characterized for physical, thermal, chemical and mechanical properties. The chemical composition analy-sis revealed that Pandanus amaryllifolius fibre has cellulose, hemicellulose, and lignin content of 48.79%, 19.95% and 18.64%, respectively. FT-IR and XRD analysis confirmed the presence of cellulose and amorphous substances in the fibre. The tensile strength of the fibre was 45.61 ± 16.09 MPa for an average fibre diameter of 368.57 ± 50.47 μm. Moisture content analysis indicated 6.00% moisture content of Pandanus amaryllifolius fi-bre. The thermogravimetric analysis showed the thermal stability of Pandanus amarylli-folius fibre up to 210 °C, which is within polymerization process temperature conditions. Overall, the finding shows that Pandanus amaryllifolius fibre may be used as alternative reinforcement particularly for a bio-based polymer matrix. Furthermore, utilization of Pandanus amaryllifolius fibre as the reinforcing agent will lead to greater development of more biopolymer products since this natural fibre can be reinforced with a synthetic and natural polymer matrix.

Author Contributions: Conceptualization, Z.N.D. and R.J.; methodology, Z.N.D. and F.A.M.Y.; formal analysis, Z.N.D.; R.J.; M.Z.S. and F.A.M.Y.; investigation, Z.N.D.; writing—original draft preparation, Z.N.D.; writing—review and editing, Z.N.D.; R.J.; R.H.A. and M.Z.S.; visualization, Z.N.D.; supervision, R.J.; project administration, Z.N.D.; funding acquisition, R.J. and R.H.A. All authors have read and agreed to the published version of the manuscript.

Funding: The research work was funded by FRGS RACER research grant RAC-ER/2019/FTKMP-CARE/F00413 and the Article Processing Charge was funded by Universiti Ma-laysia Sabah.

Institutional Review Board Statement: Not applicable.

Figure 8. Thermogravimetric analysis (TGA) and DTG curves for Pandanus amaryllifolius fibre.

4. Conclusions

The Pandanus amaryllifolius fibres were successfully extracted from plants via a wa-ter retting extraction process. The Pandanus amaryllifolius fibres were characterized forphysical, thermal, chemical and mechanical properties. The chemical composition analysisrevealed that Pandanus amaryllifolius fibre has cellulose, hemicellulose, and lignin content of48.79%, 19.95% and 18.64%, respectively. FT-IR and XRD analysis confirmed the presenceof cellulose and amorphous substances in the fibre. The tensile strength of the fibre was45.61 ± 16.09 MPa for an average fibre diameter of 368.57 ± 50.47 µm. Moisture contentanalysis indicated 6.00% moisture content of Pandanus amaryllifolius fibre. The thermogravi-metric analysis showed the thermal stability of Pandanus amaryllifolius fibre up to 210 ◦C,which is within polymerization process temperature conditions. Overall, the finding showsthat Pandanus amaryllifolius fibre may be used as alternative reinforcement particularly fora bio-based polymer matrix. Furthermore, utilization of Pandanus amaryllifolius fibre asthe reinforcing agent will lead to greater development of more biopolymer products sincethis natural fibre can be reinforced with a synthetic and natural polymer matrix.

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Author Contributions: Conceptualization, Z.N.D. and R.J.; methodology, Z.N.D. and F.A.M.Y.;formal analysis, Z.N.D.; R.J.; M.Z.S. and F.A.M.Y.; investigation, Z.N.D.; writing—original draftpreparation, Z.N.D.; writing—review and editing, Z.N.D.; R.J.; R.H.A. and M.Z.S.; visualization,Z.N.D.; supervision, R.J.; project administration, Z.N.D.; funding acquisition, R.J. and R.H.A. Allauthors have read and agreed to the published version of the manuscript.

Funding: The research work was funded by FRGS RACER research grant RACER/2019/FTKMP-CARE/F00413 and the Article Processing Charge was funded by Universiti Malaysia Sabah.

Institutional Review Board Statement: Not applicable.

Data Availability Statement: The data presented in this study are available on request fromthe corresponding author.

Acknowledgments: The authors would like to thank Ministry of Higher Education Malaysia, Univer-siti Teknikal Malaysia Melaka for the financial support through grant number RACER/2019/FTKMP-CARE/F00413, Universiti Kuala Lumpur (UniKL MICET) for the experimental support and APCwas funded by Universiti Malaysia Sabah.

Conflicts of Interest: The authors declare no conflict of interest.

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